Blast freezers are generally used in frozen food processing, and the impact-type freezer with high convective heat transfer coefficient has become the focus of freezer manufacturers and researchers. The high-speed airflow, originated from the airflow in a plenum chamber released by a nozzle structure, is critically important for a desirable impact effect. The impact effect depends largely on the structure and size of the nozzle structure. The nozzle structure of the existing impact-type freezer usually is a circular orifice plate. However, such structure leads to the problems such as low freezing rate of the frozen products in the freezing area and low uniformity during cooling process.